A battery pack consists of one or more electrochemical cells or batteries, wherein each cell typically includes a positive electrode, a negative electrode, and an electrolyte or other material for facilitating movement of ionic charge carriers between the negative electrode and positive electrode. As the cell is charged, cations migrate from the positive electrode to the electrolyte and, concurrently, from the electrolyte to the negative electrode. During discharge, cations migrate from the negative electrode to the electrolyte and, concurrently, from the electrolyte to the positive electrode.
Such batteries generally include an electrochemically active material having a crystal lattice structure or framework from which ions can be extracted and subsequently reinserted, and/or permit ions to be inserted or intercalated and subsequently extracted.
Recently, three-dimensionally structured compounds comprising polyanions (e.g., (SO4)n−, (PO4)n−, (ASO4)n−, and the like), have been devised as viable alternatives to oxide-based electrode materials such as LiMxOy, wherein M is a transition metal such as cobalt (Co). These polyanion-based compounds exhibit electrochemical and safety characteristics over other electrode active materials commercially available today.
However, electrochemical cells employing such polyanion-based compounds often suffer from poor performance and further still, failure, due to the deleterious effects caused by heat generated within the cell during charge and discharge. Such deleterious effects are especially acute when the cell is charge and discharged at high rates. Accordingly, there is a current need for a method and apparatus for dissipating heat generated in secondary electrochemical cells containing polyanion-based electrode active materials.